SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '341dc59a2493759d0f6839f1daa407e5be6e299de18c5fdb45ff9c268529bfa8' 
  AND token = 'L0tChinElAKjV2EsmMeEMzOevwZ+UlDm33j++Y2AeF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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