SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0df0295580dad5dd6b1bc678e3c315e42d37f4f0be973c5e0f6154da4412ff53' 
  AND token = 'gFg0qDVXjSWz9v+Wm/TH021wApKGv3nQL8ju608uT2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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