SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc9e8148025f50427155dff75aa2e33817e116bc540ea2f53f9b9cba01183568' 
  AND token = 'MLwWCxPOh1NU3/lrKaAtsj+3dUxrnejjC34BZLFDDQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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