SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b55e4e868014dd13ca0928d1096ffb3e73023fc6f8f1010c0b4c6b2bab082272' 
  AND token = 'UF70um94T1tQ/NhshUbPcxTvsFKjKhPAIlVGreqF4Mw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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