SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7dda2673e84390d829bc899c5c66b906c38eb18f089431ba396f935cd17871b' 
  AND token = '7dcZ6KtkBh9WZ4Hj+KsvCZwBQ1N/WgWVODj/HCHqXT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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