SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4471e6cf8d9d8f6d1ae0f6f84dca6309d37db339dde0064b2faacc83bc46656f' 
  AND token = '7SnTkjzutrTMamD5+eWzUb+Xvin1YFtYJUHbVmPqgGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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