SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acab8670f8769481fa43b911e41c31a09e6d55c1b454ad5ded4e4429846a03bf' 
  AND token = 'AyDOM+kl3aMSRLOlB0nGasU1ATWXbM0mZCglzGcdOaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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