SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '923ea0e00c4397ddbddd78e6000119e8a28d6d6748c4657398cd12978e8a2c95' 
  AND token = 'VA3LXAwKiCF/Sv/ZJYv1uRQrLrgWKhjyzEubg41PeGE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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