SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff76be47078d4c8ee627bae4cc55a0aa03da3d2723433eb0b0c15c455ebca75d' 
  AND token = 'HJeHYQICb1jv1V8Opon2evqfjsRU/Ta3mVNrPMelu1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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