SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3563a5049a4557c4dc564981f9295072605451b50340be0be1f66ff392a20512' 
  AND token = 'DCxMUzGdFqsJIz9hM+Z1oMG8AgWyUBLA28pImMC2vi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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