SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e261bf5c191010045de4a6fac36461992cb9801198c484b0b0079217e046bd23' 
  AND token = '1bYR1FgDomVn3tw+TQC++FGJjke3/E3skAV7zm14CzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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