SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '758616005f1ac1ad759c8e3789846fa12f4427b16f230e3c197754c4bfbb955b' 
  AND token = 'u4SXxowWh/tRJEQZKQvRDr5E+RUvDeGLOZmw2gshQV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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