SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5af92864ab9886123e06b05257f1f5d05cfc328a731293aca5806d8bacc43d76' 
  AND token = 'GtNdRufiOKYtTNh4ozrTDH5xdSaI+CYhA2/vpeRKpEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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