SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1d3381fd40806c1af16c61a76f39795407deec2c542205c7478e928b244bfbe' 
  AND token = 'TSxzmDFgdsYSZkhI1XIX+tZD9wuNDJ8mMNmhtGpzkDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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