SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57a08be2e6a6ffc47cf41dcc798a4c07ee482c4b03910884021adaf7e7b6d051' 
  AND token = 'OAYvUZDaPOH+oTUpZQ3imjHCqA/p2NGGEqufgHhZ4Wc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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