SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'f08c88ef6f29252ce9953b7782a838f28aef30ca05b47a6e79194d6d73d86503' 
  AND token = '3bsxHEj8LZB8/k+Aw8fdFCaxqRf/HlqHAXZrg8QezQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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