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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbb0b977c360e9f0747e7ca0ad657cc4e6480fc6424bcee541710c75d81b7e52' 
  AND token = 'n/AxPACeGbJbmRY1B7Ozn3F4lpT6ZlN+fzaqU4/6A1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}