SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c696b1f14d42bf681f5927beca17f47246db40d8d75a29bf1362c374b4f9a2e5' 
  AND token = '/8MHFh1evKyBplprHxSTJfy3ylbuXYPZzVzJ/WLHbT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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