SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6400aa64486716f6fdcd7b2a6b18e278374cf3f54d8b38a45c471b318cb9321' 
  AND token = '1v4llmicleXFI/cqzP06bB7cJKpPYMenMpV2um9nUjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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