SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51c56415e9b4d92227ad6c8e46e737053a879b2f9372a6d1d84e3cf942c1b14c' 
  AND token = 'PmGuppyWycNdVZnr0WNBuixIZJTWHTQXeniSDr5ZN6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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