SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58d83f404df42a7705eda552d3dd3201ef575e755c4534e0890d16ca1f352efe' 
  AND token = 'YCz3lELXbQkVZT/DR4nh8NH4+kn0x2MVrjNuHl4BG9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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