SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20eafa998053db471c255b1142a02769b233ab175aade99c2951a897c0e0ea6d' 
  AND token = 'ctAOSKgL0n7qbxFYEgPJIZUvJEZbNt5jMF7jB8IpFXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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