SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acaf08c51d4350e5f08d41dbaf3c65c237392e16a95be1c2de6f4539c617e37f' 
  AND token = 'b1OEO46qgs5d4Rb32m4pMSI+11NNmDEzCQYW9Osh5Ss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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