SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2dad51a736248df5c9df43f5b1a131875f890936bc944e91f9130027262d152' 
  AND token = 'cVmc1csnwC7ovLu+j4y3pU+oxSgY3jC1jKog9tWJX6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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