SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55f0d4e6eb320c9f1ae77524107dfe63e9e1b5a262320ac70055d53c3561162a' 
  AND token = 'H6vwYk32Kh5YfdSYPjrC+1sgEhkkbxibxSWyAl09l4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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