SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ef1a7d68550404c00a5bb9d204774d2f4364fef9e8795038e4a852fe78c0b39' 
  AND token = 'ouhFkBpKb/kVkMPVgabbIAesbBgzFhYk2GyQpqMYtog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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