SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6805b91a808e849c1c4b9d2e1d52a7ff36a19b9741679a7a07601ee1cb050c38' 
  AND token = 'etuHh4W/n7kkeUpaE06CdYMVXNna7njcnM91VBiHpBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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