SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b52b34c72076c5663a5df9af4a918b421062c1ef3abe8ab9534a52493bf6803a' 
  AND token = 'fyemmJRg50ilWl+m124dbWjZxKWoRnWOoOe5f/4vBmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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