SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c78c9a1625a9c20352b6c396c07addbfac0d30194efbfc76221abec25f71a113' 
  AND token = 'wuPUmtzvtd1KvD6z6dC7sbV+uVefju34ZZRUBJF6YhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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