SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e431600756a3180652216338de14e01d99b60c24b44ed81dbbadd01acd717792' 
  AND token = '+x0HBhWncJlAikeNlxxivY//KSPeiOPWiVVkboisBEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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