SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db43ea0c9111f97b32c6db0185d8e0c1a680cd1a7d1d870555e8e556323be39' 
  AND token = 'eTL5vO9HL99Cej8x3dknNREqE5McVFOgXCC/eWwqw+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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