SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2f5499253d32b3ae3de2586af25e4c1a0a58e8c954174bf16fda3337714f59b' 
  AND token = 'gt0Fo90hImXk1XOP+sdTV7+OWwxd1gd3s1K+i785ZFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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