SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20715a58249a81a438bda05de534c1efa5194f744c52fda9bc141b3e63afc0c1' 
  AND token = 'B3xq2PFJB/T/Bnc/rYfizSAQBP+qoAhdNAONDzvMIPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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