SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f21dac86284982336d0c063a0a696e9b24dade2a9b2288e82581b6fb1909a409' 
  AND token = 'eyGH+109FWMxYXcZ7vejqWtjkhtwiUbHq17CpMkGvkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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