SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67a652f1fb512e4d1f461f85a55e3f6258a8f096193d7cd5db47c8e03fad8242' 
  AND token = 'UqAirZ6bP2gejrf3oDSf713ggfomq55vvDxoDdllBTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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