SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5253c8ededb82ed2497d98f6db650ecc6dbca0eb205f07ce0c5eaa7998b3b38' 
  AND token = 'jEJLlkrxJ4ddh3acByq/TUV7ONWg2oE9AwcjdZzy15w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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