SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27a8ed561bd9b88ea2b4be64f6521eb167557065b7e311f30fbaab5cd2c51e2b' 
  AND token = 'c+0Sz79BRKgmZw2kPj/1ILnFulTI1wQ82StWyAd7Kl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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