SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3516152f5dbd883c7a87dd46af0e73674ef27b157bb72878c8a39f30f4dbd6e8' 
  AND token = '5rTcN5731lpLrKvbD0wcq7SBKUfKzPEFpmSPg0occNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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