SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66fbed76bae83e751a61fe3ddf8d8b644ade886d048187a3936c333bbe49579f' 
  AND token = '6ohsqEIjFeL2AAso1xnw+JKP05L+shQocCGiCCcWXZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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