SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e80c8df5b2c511b91f47635f79f56af816f58edb818a3716f4e11336b752a236' 
  AND token = '2gSXpWJlrTKGMLY9vSY24zaSeiHUwekhihjC7yQeOYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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