SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6514597c2c5ba853dc42626add16bec26e4eaff2838fdb4dbaf4fea4527c88a6' 
  AND token = 'Bw5Zlm2cg4fy0kseC16rrqvYVehRsoOU89GBcAgpwf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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