SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '1799c7f1ecded74056c4b3eb86cbfd267afd638211b9decdb7949474bd15393b' 
  AND token = 'i6/fGR+PK3whpfUhdJhc+fp19t31JnFYmLxrLpZzlpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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