SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bff05bc88e82858d1e0e86c0515a838ab385b94041924b4aca4fe883f56c52a6' 
  AND token = 'aEBelAQAbMGLUpwYMGGrjI3NmvVLNDtFSBTscZBm5GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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