SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5b542282bc2fcc3ecc59d0a0ebb752f853079751c97c174e2edc3bdb1850c79' 
  AND token = 'mKs2cd9SIRli4gzV40/aJk2csSZWDyUMCESNVVFKEgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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