SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a75b4b1d1dfd460f9d63acc630699f9ee0a39c60b8a0519b20c54def69b188c' 
  AND token = 'HU8hNEOXmc0GSLKR3IBnKTrY7j+o3vP9FYvnuRbqVpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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