SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6b6001fff528343adf7f5838597ea583cfd271588621280ecea428a07d4d9a0' 
  AND token = 'yMlfNzjYz7ol1ffAgLSRiCgy42jKnzN1D63frUgNXms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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