SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f82eb06518ee063579d9afdfebd62d6340d14f1b0ebb6935606b35a126bd4b50' 
  AND token = 'yTtNBfXeVqcZGnmCxxhQGuPJUUMjfek3RFq8KYQ/aZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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