SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3fc752fcb74cb731c6d1dd94d6083f0ca735967540ef27738bd29a36e68fbf7' 
  AND token = 'Bhx+Dp//vRs1NXbgee1zXItJwMx+yz17vwRRnxNAPxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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