SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e697758c34aa2f890808264045f552789834417fc809f4d1b6d2409fa636f0c' 
  AND token = 'ZhSjt71CBqWDbJVX0IGw8Z2qenXW+9zcrQgy4mWJj4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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