SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6270dba65153ae6d61a2fec9188c18dee9ef2150a6a2d4240428411a099c915' 
  AND token = 'rhczSzUvhjHDnLV3CxQg8Iq/6WrfK4PSuMXHurbPNYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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