SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2e92d84248c7effd9247134d7d3cb5bfc52074644fdd2be8cf600adcd2158c9' 
  AND token = 'oCwFghtoeizN6SDbKTiXtiExiCnfndcglvqHSqIJKIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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