SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2763c9e1bc26fb56cab257f28cf3b30f61a63347ea5fd4e15ce3e75d47dabd3' 
  AND token = 'vbmMQs3qtfiB+gXGwJPO+rZsR/CpAhn8enC/LQ+5W6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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