SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90e112215b14095ca12b720cf7b83ece066d3c73b35deb9777c483bf679cbf15' 
  AND token = 'C3cJB0e4c2gZYpmxuGW6mS7h5dexewybBmrwcCg5xvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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