SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '942db4a57241ff9d107230ed11d82bbc37d294e206d99ef2046eb565746112f2' 
  AND token = 'zbmcV3dQrDnfBJyp5AoF/3WUMk5giixvbMi34WHrEiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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