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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8d3278a466dba83a93567ef5888fab15c1fa147cf9b06aeed16e1e54d08d18c' 
  AND token = 'PMWN0x74YIdjF/OJvgE0QJIcYs3Sj77BMJujQw5JVJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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