SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbaa6d09baa939ea0b85249d8273b2299f75a7cc0befe0801a1ec998536fff4a' 
  AND token = '9m0HmL7RRwbelhkcR6++Vd+AqR/LTwaGXSDBfKdp5G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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