SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26b3f15f34f0a2b14793e39251d9a00b3709acc618ea8d2efa188198f33aafd4' 
  AND token = 'qw1BKtGSxceHl9t8B7FznenPqttGq7wyjFPHMAg5WgE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}