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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6c3bf27e5e898523229ae3c250b72a42cf65e274e83856fb78e5bef22764421a' 
  AND token = 'I+lBopHh/T4V5jRlp2seNwPOLxXVjdmhN6ynMqSwmh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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