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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3f4a0221ca4e10c80570fbd7b971c36ad62ce7de0c146d369fb75ca4d9e6eb3' 
  AND token = 'UvcVTg0/FAitQnUytqMqSmq0N4PuSglDKD0NDAUyyAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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