SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c76c98fc2ca86f49a2e19be3327f2a53f9824c0c52b9ac6715be25509de9502' 
  AND token = 'TGlCcMOIUEXSyyOxipKEQAQjsvUgS+IjBGwkrr11mac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00074

JSON explain

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