SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da2d789b57660f4fc899666dec4125372deb20b8904f0c4646298299ba0b3bf3' 
  AND token = 'uyD0ayocbWDVWvM/M4RFgW59PNce3wJScDfbkCVeCeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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