SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e780637b3b2e13039a232d67107d8aac9f5617fc2d53b239b182f0a597d4c5cb' 
  AND token = 'YtLExILE+qFWzwh+SIPSRlYHzRCeoTDUHNgIKPOIdlw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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