SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81d12e1bcc763a4414c82b51282f73a5a650fb2d577474a13d32829cc45077fe' 
  AND token = 'os9BdAKE4ya+46pMIWLKbIa4e3dc0pUTJRDE/NvDNQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}