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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81d06f68c9f8da0a1d01f1800d7e5c7f354b59681082ccb3c9b8fd0b576198cd' 
  AND token = 'amCmT6tHpSY3a6sLJ6P8zht/sIdqw8YnN2k52cKtSsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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