SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a31419df567cb27b321086877937bf1a5efaf2bbb0242baf2baa625006e1ed0' 
  AND token = 'kmS3Qx8E4s0IrjYo8Pk1avBVFkBPycbWAcd4rs6m/wA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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