SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b72f4236996c16fdc536678ceae13b7895acd2c186e4096135ad9f4ad02b27f1' 
  AND token = 'KExX9O5zW43MRZC+XM6n6ycQzT/lURefTri+qcPja44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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